Olefin metathesis

ABSTRACT

The metathesis process is used: (A) for the production of propylene from the metathesis of 2-butene and ethylene wherein the propylene product is removed concurrently by fractional distillation by which the removal of the propylene product disturbs the equilibrium concentration and allows for higher conversions; (B) for the production of detergent range olefins from the metathesis of C 15  and heavier olefins with C 9  and lighter olefins wherein the detergent range olefin product is removed concurrently by fractional distillation in which the removal of the detergent range olefin product disturbs the equilibrium concentration and allows for higher conversions with less side reactions; (C) for the production of 2-methyl-2-butene and propylene from the metathesis of 2-butene and isobutylene wherein the propylene product and 2-methyl-2-butene product is removed concurrently by fractional distillation in which the removal of the product disturbs the equilibrium concentration and allows for higher conversions; and (D) for the production of tetramethylethylene from the metathesis of isobutylene with itself in a distillation column reactor and/or the reaction of diisobutylene produced in the CD reactor with the ethylene produced to produce neohexene.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a process for the metathesis ofolefins. More particularly the invention relates to a process whereinthe catalyst is part of a distillation structure and the products aresimultaneously separated from the reactants and each other by fractionaldistillation during the reaction.

[0003] 2. Related Art

[0004] Broadly metathesis has been defined as a chemical reaction inwhich an element or radical in one compound changes places with anotherelement or radical in another compound. See The Van Nostrand Chemist'sDictionary, D. Van Nostrand Company, Inc., 1953, page 463. Morespecifically olefin metathesis can be defined as the redistribution ofalkylidene moieties to give a mixture of olefins. In effect, thisreaction takes place via cleavage of the olefin double bond. Generallythe reactions of olefinic molecules in the presence of metal-containingcatalysts to produce other olefinic molecules are known in the art as“disproportionation”, “dismutation” or “metathesis” reactions. Themetathesis reactions are of considerable interest because of theversatility of the reaction and the numerous olefinic hydrocarbonsavailable from petrochemical sources which are suitable for use in thereaction to yield useful products. One such reaction is the metathesisof propylene with itself to produce n-butene and ethylene. See, forexample, U.S. Pat. No. 4,046,832. The reverse reaction is the metathesisof ethylene with n-butene to produce propylene and is disclosed in U.S.Pat. No. 5,026,936. Another use of the metathesis reaction is to produce2-methyl-2-butene from the reaction of 2-methyl-1-propene and 2-butene.See U.S. Pat. No. 3,702,827.

[0005] Finally, the simultaneous disproportionation of olefins andfractional distillation is reported in U.S. Pat. No. 4,709,115. Thereinthe disproportionation of butene with itself to produce ethylene orpropylene and hexene or pentenes is disclosed.

[0006] Catalysts that are known to catalyze the metathesis include theoxides of tungsten, rhenium and cobalt/molybdenum.

SUMMARY OF THE INVENTION

[0007] Briefly the present invention relates to metathesis reactioncarried out a in distillation column reactor, that is, reaction andfractional distillation of the reactants and products are carried outconcurrently in the distillation column reactor wherein the catalyst maybe in the form to act as a distillation structure or part of adistillation structure or alternatively the catalyst may be located inbeds or zones preferably located within the distillation column reactor.

[0008] One embodiment of the present invention comprises the productionof propylene from the reaction of 2-butene with ethylene in adistillation column reactor. Preferably the catalyst is supplied in theform to act as a distillation structure or part of a distillationstructure and loaded into the upper portion of a distillation columnreactor. The 2-butene is fed above the bed and the ethylene is fed belowthe bed. Product propylene is taken as overhead and any heavies producedare removed as bottoms.

[0009] In a second embodiment the present invention relates to a processfor the production of higher molecular weight olefins useful in themanufacture of detergents. More particularly the invention relates tothe metathesis of olefins having higher molecular weight than thatdesired with lower molecular olefins to produce the desired molecularweight olefins.

[0010] In another embodiment the present invention comprises themetathesis of isobutylene with 2-butene to produce 2-methyl-2-butene andpropylene. The catalyst is loaded into the upper portion of adistillation column reactor. The isobutylene is fed below the bed.Product 2-methyl-2-butene is taken as bottoms while propylene is removedas overheads.

[0011] Another embodiment of the present invention comprises themetathesis of isobutylene with itself to produce 2,3-dimethyl-2-butene(tetramethylethylene or TME) and ethylene. The catalyst is loaded intothe upper portion of a distillation column reactor. The isobutylene isfed below the bed. Product TME is taken as bottoms along with any C₈=orC₁₂=oligomerization product. Ethylene is removed as overheads. The TMEis separated from the heavy oligomers by fractional distillation. TheC₈=oligomers are then separated from the C₁₂=oligomers by fractionaldistillation and fed to a single pass down flow reactor with ethylenefor metathesis to 3,3-dimethyl-1-butene (neohexene).

BRIEF DESCRIPTION OF THE DRAWING

[0012]FIG. 1 is schematic flow diagram of an embodiment thatdemonstrates the use of catalytic distillation to produce propylene fromthe metathesis of ethylene and 2-butene.

[0013]FIG. 2 is a schematic flow diagram of an embodiment for theproduction of higher olefins.

[0014]FIG. 3 is a schematic flow diagram of an embodiment for theproduction of 2-methyl-2-butene and propylene.

[0015]FIG. 4 is a schematic flow diagram of an embodiment for theproduction of TME and neohexene.

[0016]FIG. 5 is a schematic flow diagram of an embodiment for theproduction of neohexene.

DETAILED DESCRIPTION OF THE INVENTION

[0017] The reactions are preferably carried out under conditions ofcatalytic distillation. In a catalytic distillation, i.e., the catalystserves as a distillation component

[0018] The catalytic material is preferably a component of adistillation system functioning as both a catalyst and distillationpacking, i.e., a packing for a distillation column having both adistillation function and a catalytic function: for example, rings,saddles, balls, irregular, sheets, tubes, spirals, packed in bags (asdescribed in U.S. Pat. No. 4,242,530), plated on grills or screens,reticulated polymer foams (the cellular structure of the foams must besufficiently large so as not to cause high pressure drops through thecolumn or otherwise arranged, such as in chunks or concentration tubesto allow vapor flow) or honeycomb monoliths. The reaction system can bedescribed as heterogenous since the catalyst remains a distinct entity.

[0019] A preferred catalyst structure for use in the distillation columnreactors for the present hydrogenations comprises flexible, semi-rigidopen mesh tubular material, such as stainless steel wire mesh, filledwith a particulate catalytic material

[0020] One new catalyst structure developed for use in hydrogenations isdescribed in U.S. Pat. No. 5,266,546 which is incorporated herein in itsentirety. Another catalyst structure particularly suited forhydrogenations is described in U.S. Pat. No. 5,431,890 which isincorporated herein in its entirety.

[0021] U.S. Pat. No. 4,242,530 and U.S. Pat. No. 4,443,559 which areincorporated herein, disclose particulate catalyst in a plurality ofpockets in a cloth belt or wire mesh tubular structures, which issupported in the distillation column reactor by open mesh knittedstainless steel wire by twisting the two together into a helix. U.S.Pat. No. 5,348,710, which is incorporated herein, describes severalother suitable structures in the prior art and discloses new structuressuitable for this process.

[0022] Other catalytic distillation structures useful for this purposeare disclosed in U.S. Pat. Nos. 4,731,229 and 5,073,236 which are alsoincorporated by reference.

[0023] In addition to the catalytic systems described above, reactivedistillation systems such as those disclosed in U.S. Pat. Nos.4,536,373, 4,774,364, 4,847,430 and 5,510,089, which are incorporatedherein, may be used to carry out the present process.

[0024] The particulate catalyst material may be a powder, smallirregular chunks or fragments, small beads and the like. The particularform of the catalytic material in the cloth pockets is not critical, solong as sufficient surface area is provided to allow a reasonablereaction rate. The sizing of catalyst particles can be best determinedfor each catalytic material (since the porosity or available internalsurface area will vary for different material and of course affect theactivity of the catalytic material).

[0025] The distillation column reactor can be appreciated to contain avapor phase and some liquid phase as in any distillation. The success ofthe concurrent distillation and reaction approach lies in anunderstanding of the principles associated with distillation. First,because the reaction is occurring concurrently with distillation, theinitial reaction products are removed from the reaction zone as quicklyas possible. Second, because all the components are boiling thetemperature of reaction is controlled by the boiling point of themixture at the system pressure. The heat of reaction simply creates moreboil up, but no increase in temperature. Third, the reaction has anincreased driving force because the reaction products have been removedand cannot contribute to a reverse reaction (LeChatelier's Principle).

[0026] As a result, a great deal of control over the rate of reactionand distribution of products can be achieved by regulating the systempressure. Also, adjusting the throughput (residence time=liquid hourlyspace velocity⁻¹) gives further control of product distribution anddegree of conversion to metathesis product.

[0027] The temperature in a distillation column reactor is determined bythe boiling point of the liquid mixture present at any given pressure.The temperature in the lower portions of the column will reflect theconstitution of the material in that part of the column, which will behigher than the overhead; that is, at constant pressure a change in thetemperature of the system indicates a change in the composition in thecolumn. To change the temperature the pressure is changed. Temperaturecontrol in the reaction zone is thus effected by a change in pressure;by increasing the pressure, the temperature in the system is increased,and vice versa.

[0028] A reflux is preferably included in the system. The reflux ratiocould vary over the rate 0.5:1 to 33:1. In practice, the higher ratiomay be used to compensate for a short catalyst bed such as required forexperimental work. In commercial size units the catalyst bed would beprovided so that lower reflux and hence higher unit productivity couldbe obtained at lower operating cost.

[0029] Suitable catalysts for the metathesis are the supported oxides ofcobalt, molybdenum, rhenium or mixtures of cobalt and molybdenum oxides.Either silica or alumina based supports for the oxides may be used. Thedistillation column reactor is generally operated at an overheadpressure to result in a catalyst bed temperature of 100-200° C. forCoOMoO₃ catalyst and about room temperature for the Re₂O₇ catalystbearing in mind the effect of pressure on temperature as discussedabove.

[0030] The specific metathesis reactions of interest are:

[0031] I. Propylene Process

[0032] The reaction of 2-butene with ethylene to produce propylenebecause of the availability of the 2-butene and the value of propylene.The 2-butene can be produced from the dimerization of ethylene. Thereaction is reversible in fixed bed reactors for a given residence timeand may be written as follows:

CH₂═CH₂+CH₃CH═CHCH₃

2 CH₃CH₂═CH₂

[0033] In a distillation column reactor, the equilibrium is constantlydisturbed, thus although the equilibrium concentration of propylene at agiven temperature is rather low, the removal of the propylene as anoverhead product constantly drives the reaction to increase productionof propylene. Adjusting the throughput gives further control of productdistribution and degree of conversion to propylene. The production ofundesirable side products, i.e., the isomerization of 2-butene to1-butene, followed by their metathesis to pentenes and hexenes, isprevented or minimized.

[0034] Another advantage of the catalytic distillation reactor is thatthe feeds will be dried by azeotropic distillation allowing long periodsof catalytic activity without the special drying steps that wouldotherwise be necessary. The necessity for dry feed is indicated in U.S.Pat. No. 3,340,322 where the dried feed is specified for the examples.

[0035] Referring now to the FIG. 1 a simplified flow diagram of thepropylene process may be seen. The reaction distillation column 10 isseen to contain a bed 12 of the catalyst in the upper portion of thecolumn. Below the catalyst bed 12 is a stripping section 14 containingstandard distillation structure such as sieve trays, bubble cap trays orinert packing. Above the catalyst bed 12 is a rectification section 16also containing standard distillation structure.

[0036] The 2-butene feed in liquid form is fed above the catalyst viaflow line 102 and the ethylene is fed as gas below the catalyst bed viaflow line 104. The ethylene flows upward into the bed 12 and reacts toform propylene which is removed as overheads via flow line 106 alongwith the small amount of unreacted ethylene. The column is operated tokeep the 2-butene concentrated within the catalyst bed by internalreflux with feed being added as necessary to make up that reacted. Therectification section 16 insures that the 2-butene is separated from theC₃ and lighter material (propylene product and unreacted ethylene). The2-butene is present in large excess to the ethylene, i.e. 25 moles2-butene to 1 mole ethylene. A bottoms draw via flow line 108 is takento remove any heavier by products produced in the reactor.

[0037] The overheads in flow line 106 is cooled in condenser 20 and theliquid collected in receiver/separator 30. A portion of the liquidproduct may be returned to the distillation column reactor 10 as refluxvia flow line 110. Product propylene can be removed as a gas via flowline 112 or liquid via flow line 114.

[0038] If desirable the ethylene feed may be contained in a mixedethane/ethylene stream in which case the ethane would be removed asoverheads along with the propylene and unreacted ethylene. The ethaneand unreacted ethylene could then be separated in receiver separator 30and removed via flow line 112 with the product propylene being removedvia flow line 114. Any water is removed overhead as an azeotrope andphases out in receiver/separator 30 from which it is recovered via line116.

[0039] II. Higher Olefin Process

[0040] The specific metathesis reaction of interest is the reaction ofhigher molecular olefins (C₁₅+) with C₃-C₈ olefins to produce detergentrange olefins (C₁₀-C₁₄). Conversion is limited by equilibrium in fixedbed straight pass reactors. In a catalytic distillation, i.e., thecatalyst may serve as a distillation component, the equilibrium isconstantly disturbed, thus although the equilibrium concentration of thedetergent range olefins at a given temperature is rather low, theremoval of the product as bottoms product constantly drives the reactionto increase production of the desired olefins.

[0041] Referring now to FIG. 2 a simplified flow diagram of the processmay be seen. The reaction distillation column 210 is seen to contain abed 212 of the catalyst in the upper portion of the column. Below thecatalyst bed 212 is a stripping section 214 containing standarddistillation structure such as sieve trays, bubble cap trays or inertpacking. Above the catalyst bed 212 is a rectification section 216 alsocontaining standard distillation structure.

[0042] The heavy olefin feed is fed above the catalyst bed in liquidform via flow line 202 and the light olefins are fed below the catalystbed via flow line 204. The light olefins flow upward into the bed 212and react with the heavy olefins to form the desired detergent rangeolefins which are removed as bottoms via flow line 208 along with theunreacted heavier olefins. The bottoms from the distillation columnreactor are fed via flow line 208 to bottoms splitter 260 where thedetergent range olefins are taken as overheads via flow line 220. Theheavier olefins are removed from splitter 260 as bottoms via flow line222 and are recycled back to the feed in flow line 202.

[0043] The column is operated to keep the C₅-C₈ olefins concentratedwithin the catalyst bed by internal reflux with feed being added asnecessary to make up that reacted. The rectification section 216 insuresthat these olefins are refluxed within the column. Unreacted lighterolefins and any light olefins produced by the reaction are removed asoverheads via flow line 206.

[0044] The overheads are passed first to a debutanizer column 240 wherethe C₄ and lighter components are removed as overheads. The bottoms,consisting mostly of C₅-C₈ olefins are recycled to the distillationcolumn reactor as external reflux via flow 211. The C₄ and lighterolefins from the debutanizer are fed to a deethanizer 250 wherein the C₂and lighter olefins and any water in the feed are taken as overheads viaflow line 213 to be recycled to an oligomerization unit to produce moreheavy olefins. The C₃ and C₄ olefins are removed as bottoms via flowline 215 and recycled with the light olefin feed in flow line 204.

[0045] III. 2 MB2 and Propylene

[0046] The specific metathesis reaction of interest is the metathesis ofisobutylene with 2-butene to produce 2-methyl-2-butene and propylene.The reaction is reversible in fixed bed straight pass reactors for agiven residence time. The reaction may be written as follows:

[0047] isobutylene 2-butene 2-methyl-2-butene propylene

[0048] The 2-methyl-2-butene product is useful as a precursor for theproduction of isoprene. Propylene is also a useful olefin for polymerproduction.

[0049] In a catalytic distillation, i.e., the catalyst serves as adistillation component, the equilibrium is constantly disturbed, thusalthough the equilibrium concentration of propylene at a giventemperature is rather low, the removal of the propylene as an overheadproduct constantly drives the reaction to increase production ofpropylene.

[0050] Referring now to FIG. 3 a simplified flow diagram of the processmay be seen. The reaction distillation column 310 is seen to contain abed 312 of the catalyst in the upper portion of the column. Below thecatalyst bed 312 is a stripping section 314 containing standarddistillation structure such as sieve trays, bubble cap trays or inertpacking. Above the catalyst bed 312 is a rectification section 316 alsocontaining standard distillation structure.

[0051] The isobutylene feed is fed into the catalyst bed 312 in liquidform via flow line 304. Unreacted isobutylene and product propylene areremoved as overheads via flow line 306. The isobutylene is condensed inpartial condenser 320 and collected and separated from the propylene inreceiver 330. The liquid isobutylene may be returned to the distillationcolumn 310 as reflux via flow line 311 or removed via flow line 315.Uncondensed materials are removed via flow line 313. The product2-methyl-2-butene is recovered as bottoms via flow line 308. The2-butene is refluxed internally within the distillation column reactor310.

[0052] IV. TME/Neohexene Process

[0053] The metathesis of isobutylene with itself and the metathesis ofdiisobutylene with ethylene are both reversible in fixed bed reactorsfor a given residence time and may be written as follows:

[0054] The two reactions are mutually supportive. Especially when it isconsidered that the isobutylene can oligomerize in the first reaction toform diisobutylene (not shown) which is useful in the second and theisobutylene produced in the second can be used in the first. Also theethylene produced in the first can be used in the second.

[0055] The metathesis of isobutene to TME (1) is ideally suited to beingcarried out in a distillation column reactor. By adjusting thethroughput, the product distribution and degree of conversion to TME andthe degree of diisobutene oligomerization can be controlled.

[0056] The metathesis of diisobutylene and ethylene (2) is anticipatedto be carried out in a standard fixed bed single pass reactor utilizingthe same or similar catalyst as used in the first reaction. However, ifpracticable the use of a second distillation column reactor is includedin the scope of the invention.

[0057] Referring now to the FIG. 4 a simplified flow diagram of thecombined TME/neohexene process may be seen. The reaction distillationcolumn 410 is seen to contain a bed 412 of the catalyst in the upperportion of the column. Below the catalyst bed 412 is a stripping section416 containing standard distillation structure such as sieve trays,bubble cap trays or inert packing. Above the catalyst bed 412 is arectification section 414 also containing standard distillationstructure.

[0058] The isobutylene feed is fed into the catalyst bed 412 in liquidform via flow line 401. Unreacted isobutylene and product ethylene areremoved as overheads via flow line 402. The isobutylene is condensed inpartial condenser and collected and separated from the ethylene inreceiver 430. The liquid isobutylene may be returned to the distillationcolumn 410 as reflux via flow line 403 or removed via flow line 404. Theproduct TME along with any oligomers are removed as bottoms via flowline 406.

[0059] The bottoms in flow line 406 are fed to a distillation column 440where the product TME is separated as overheads via flow line 407 fromthe heavy oligomers which are taken as bottoms via flow line 408. Theoligomers are further separated in distillation column 450 where thediisobutylene is taken as overheads. The C₁₂=+ oligomers are removed asbottoms via flow line 411.

[0060] The diisobutylene in flow line 409 is fed to reactor 460 whichcontains a fixed bed 462 of metathesis catalyst. A dryer (not shown) maybe necessary to remove water in the overheads (line 405) before entryinto reactor 460. The ethylene in flow line 405 from the receiver 430 iscombined with recycle ethylene from flow line 417 and fed to reactor 460via flow line 413. In reactor 460 the diisobutylene reacts with ethyleneto produce neohexene and isobutylene. The effluent from the reactor inflow line 415 is fed to distillation column 470 where unreacted ethyleneis separated as overheads via flow line 417 from the product neohexeneand isobutylene which are taken as bottoms via flow line 419. Thebottoms in flow line 419 are fed to another distillation column 480wherein the product neohexene is separated from the isobutylene. Theisobutylene is taken as overheads via flow 423 and recycled back to thedistillation column reactor 410. Product neohexene is taken as bottomsvia flow line 421.

[0061] In FIG. 5 the neohexene process alone is shown. The process isthe same as that for the TME/neohexene process, except that the column410 is operated to maximize diisobutene production as shown in U.S. Pat.No. 4,242,530, which is incorporated herein, column 440 is eliminatedand the bottoms from the CD column go directly to splitter 450. Theoverhead 402 comprises unreacted isobutylene, other C₄'s and lowerboiling components in minor amounts. Make up ethylene for the metathesisis supplied through line 420. The catalyst bed 412 comprises an acidiccation resin as described in the patent.

The invention claimed is:
 1. A metathesis process for (A) the productionof propylene from the metathesis of 2-butene and ethylene comprising thesteps of: (a) feeding a first stream comprising ethylene to adistillation column reactor containing a fixed bed of metathesiscatalyst, (b) feeding a second stream comprising 2-butene to saiddistillation column reactor, (c) concurrently in said distillationcolumn reactor (i) contacting said 2-butene and said ethylene with saidfixed bed metathesis catalyst so as to react at least a portion of saidethylene with at least a portion of said 2-butene to produce propyleneand create a reaction mixture containing unreacted 2-butene, unreactedethylene and propylene product and (ii) separating the unreactedethylene and propylene product from the unreacted 2-butene by fractionaldistillation and (d) removing the unreacted ethylene and propyleneproduct from said distillation column reactor as overheads product; (B)the production of detergent range olefins from the metathesis of C₁₅ andheavier olefins comprising the steps of: (a) feeding a first streamcomprising C₉ and lighter olefins to a distillation column reactorcontaining a fixed bed of metathesis catalyst, (b) feeding a secondstream comprising C₁₅ and heavier olefins to said distillation columnreactor, (c) concurrently in said distillation column reactor: (i)contacting said C₉ and lighter olefins and said C₁₅ and heavier olefinswith said fixed bed metathesis catalyst so as to react at least aportion of said C₉ and lighter olefins with at least a portion of saidC₁₅ and heavier olefins to produce detergent range olefins and create areaction mixture containing unreacted C₉ and lighter olefins, unreactedC₁₅ and heavier olefins and detergent range olefin product and (ii)separating the unreacted C₁₅ and heavier olefins and detergent rangeolefin from the C₉ and lighter olefins by fractional distillation and(d) removing the unreacted C₁₅ and heavier olefins and detergent rangeolefin from said distillation column reactor as bottoms product; (C) theproduction of 2-methyl-2-butene and propylene from the metathesis ofisobutylene and 2-butene comprising the steps of: (a) feeding a firststream comprising isobutylene to a distillation column reactorcontaining a fixed bed of metathesis catalyst, (b) feeding a secondstream comprising 2-butene to said distillation column reactor, (c)concurrently in said distillation column reactor (i) contacting said2-butene and said isobutylene with said fixed bed metathesis catalyst soas to react at least a portion of said isobutylene with at least aportion of said 2-butene to produce propylene and 2-methyl-2-butene andcreate a reaction mixture containing unreacted 2-butene, unreactedisobutylene, propylene product and 2-methyl-2-butene product and (ii)separating the unreacted isobutylene and propylene product from theunreacted 2-butene and 2-methyl-2-butene product by fractionaldistillation, (d) removing the unreacted isobutylene and propyleneproduct from said distillation column reactor as overheads product, and(e) removing the 2-methyl-2-butene product from said distillation columnreactor as bottoms; or (D) the production of tetramethylethylene fromthe metathesis of isobutylene with itself comprising the steps of: (a)feeding isobutylene to a distillation column reactor containing a fixedbed of metathesis catalyst, (b) concurrently in said distillation columnreactor, (i) contacting said isobutylene with said fixed bed metathesiscatalyst so as to react at least a portion of said isobutylene toproduce tetramethylethylene and ethylene and create a reaction mixturecontaining unreacted isobutylene, ethylene and tetramethylethyleneproduct and (ii) separating the ethylene and unreacted isobutylene fromthe tetramethylethylene by fractional distillation, (c) removing theethylene and isobutylene from said distillation column reactor asoverheads product and (d) removing the tetramethylethylene product fromsaid distillation column reactor as bottoms.
 2. The metathesis processaccording to claim 1 for the production of propylene from the metathesisof 2-butene and ethylene comprising the steps of: (a) feeding a firststream comprising ethylene to a distillation column reactor containing afixed bed of metathesis catalyst, (b) feeding a second stream comprising2-butene to said distillation column reactor, (c) concurrently in saiddistillation column reactor (i) contacting said 2-butene and saidethylene with said fixed bed metathesis catalyst so as to react at leasta portion of said ethylene with at least a portion of said 2-butene toproduce propylene and create a reaction mixture containing unreacted2-butene, unreacted ethylene and propylene product and (ii) separatingthe unreacted ethylene and propylene product from the unreacted 2-buteneby fractional distillation and (d) removing the unreacted ethylene andpropylene product from said distillation column reactor as overheadsproduct.
 3. The process according to claim 2 wherein said metathesiscatalyst is prepared in the form of a catalytic distillation structure.4. The process according to claim 3 wherein the unreacted 2-butene ismaintained in said fixed bed by internal reflux.
 5. The processaccording to claim 3 wherein said catalyst bed comprises the oxides ofsupported cobalt and molybdenum.
 6. The process according to claim 3wherein said catalyst bed comprises the supported oxide of rhenium. 7.The process according to claim 2 wherein said fixed bed metathesiscatalyst comprises supported cobalt and molybdenum oxides catalystprepared in the form of a catalytic distillation structure andcomprising the steps of: (e) maintaining the unreacted 2-butene in saidfixed bed by internal reflux; and (f) removing any reaction productheavier than 2-butene from distillation column reactor as bottoms. 8.The metathesis process according to claim 1 for the production ofdetergent range olefins from the metathesis of C₁₅ and heavier olefinscomprising the steps of: (a) feeding a first stream comprising C₉ andlighter olefins to a distillation column reactor containing a fixed bedof metathesis catalyst, (b) feeding a second stream comprising C₁₅ andheavier olefins to said distillation column reactor, (c) concurrently insaid distillation column reactor: (i) contacting said C₉ and lighterolefins and said C₁₅ and heavier olefins with said fixed bed metathesiscatalyst so as to react at least a portion of said C₉ and lighterolefins with at least a portion of said C₁₅ and heavier olefins toproduce detergent range olefins and create a reaction mixture containingunreacted C₉ and lighter olefins, unreacted C₁₅ and heavier olefins anddetergent range olefin product and (ii) separating the unreacted C₁₅ andheavier olefins and detergent range olefin from the C₉ and lighterolefins by fractional distillation and (d) removing the unreacted C₁₅and heavier olefins and detergent range olefin from said distillationcolumn reactor as bottoms product.
 9. The process according to claim 8wherein said metathesis catalyst is prepared in the form of a catalyticdistillation structure.
 10. The process according to claim 9 whereinunreacted C₅-C₈ olefin is maintained in said fixed bed by internalreflux.
 11. The process according to claim 9 wherein said catalyst bedcomprises the supported oxides of cobalt and molybdenum.
 12. The processaccording to claim 9 wherein said catalyst bed comprises the supportedoxide of rhenium.
 13. The process according to claim 9 wherein saidbottoms product is fractionated to separate the detergent range olefinsfrom the C₁₅ and heavier olefins.
 14. The process according to claim 13wherein at least a portion of the C₁₅ and heavier olefins separated fromsaid bottoms product are recycled as feed to said distillation columnreactor.
 15. The process according to claim 9 wherein unreacted C₉ andlighter olefins are removed from said distillation column reactor asoverheads and separated by fractional distillation into a C₅ and heavierolefin stream, a C₃-C₄ olefin stream and a C₂ olefin stream and said C₅and heavier olefin stream is returned to said distillation columnreactor as reflux.
 16. The process according to claim 15 wherein saidC₃-C₄ olefin stream is recycled to said distillation column with saidfirst stream.
 17. The metathesis process according to claim 1 for theproduction of 2-methyl-2-butene and propylene from the metathesis ofisobutylene and 2-butene comprising the steps of: (a) feeding a firststream comprising isobutylene to a distillation column reactorcontaining a fixed bed of metathesis catalyst, (b) feeding a secondstream comprising 2-butene to said distillation column reactor, (c)concurrently in said distillation column reactor (i) contacting said2-butene and said isobutylene with said fixed bed metathesis catalyst soas to react at least a portion of said isobutylene with at least aportion of said 2-butene to produce propylene and 2-methyl-2-butene andcreate a reaction mixture containing unreacted 2-butene, unreactedisobutylene, propylene product and 2-methyl-2-butene product and (ii)separating the unreacted isobutylene and propylene product from theunreacted 2-butene and 2-methyl-2-butene product by fractionaldistillation, (d) removing the unreacted isobutylene and propyleneproduct from said distillation column reactor as overheads product, and(e) removing the 2-methyl-2-butene product from said distillation columnreactor as bottoms
 18. The process according to claim 17 wherein saidmetathesis catalyst is prepared in the form of a catalytic distillationstructure.
 19. The process according to claim 18 wherein the unreacted2-butene is maintained in said fixed bed by internal reflux.
 20. Theprocess according to claim 18 wherein said catalyst bed comprises thesupported oxides of cobalt and molybdenum.
 21. The process according toclaim 18 wherein said catalyst bed comprises the supported oxide ofrhenium.
 22. The metathesis process according to claim 1 for theproduction of tetramethylethylene from the metathesis of isobutylenewith itself comprising the steps of: (a) feeding isobutylene to adistillation column reactor containing a fixed bed of metathesiscatalyst, (b) concurrently in said distillation column reactor, (i)contacting said isobutylene with said fixed bed metathesis catalyst soas to react at least a portion of said isobutylene to producetetramethylethylene and ethylene and create a reaction mixturecontaining unreacted isobutylene, ethylene and tetramethylethyleneproduct and (ii) separating the ethylene and unreacted isobutylene fromthe tetramethylethylene by fractional distillation, (c) removing theethylene and isobutylene from said distillation column reactor asoverheads product and (d) removing the tetramethylethylene product fromsaid distillation column reactor as bottoms.
 23. The process accordingto claim 22 wherein said metathesis catalyst is prepared in the form ofa catalytic distillation structure.
 24. The process according to claim23 wherein at least a portion of said condensed unreacted isobutylene isreturned to said distillation column reactor as reflux.
 25. The processaccording to claim 23 wherein a portion of the isobutylene isoligomerized to diisobutylene and heavier products which are removedalong with said tetramethylethylene in said bottoms and furthercomprising the steps of: (e) separating said tetramethylethylene fromsaid diisobutylene and heavier oligomers by fractional distillationwherein said tetramethylethylene is removed as a second overheads andsaid diisobutylene and heavier oligomers are removed as a secondbottoms.
 26. The process according to claim 25 wherein saiddiisobutylene is separated from said heavier oligomers by fractionaldistillation.
 27. The process according to claim 26 wherein at least aportion of said diisobutylene is reacted with at least a portion of theethylene from said separator in a reactor containing a second fixed bedof metathesis catalyst to produce neohexene and isobutylene.
 28. Theprocess according to claim 27 wherein additional ethylene above thatfrom said separator is fed to said fixed bed reactor.
 29. The processaccording to claim 27 wherein the effluent from said fixed bed reactoris fractionated to separate the isobutylene from the neohexene.
 30. Theprocess according to claim 27 wherein at least one of said catalyst bedscomprises the supported oxides of cobalt and molybdenum.
 31. The processaccording to claim 27 wherein at least one of said catalyst bedscomprises the supported oxide of rhenium.
 32. An integrated process forthe production of tetramethylethylene and neohexene comprising the stepsof: (a) feeding isobutylene to a distillation column reactor containinga first fixed bed of metathesis catalyst prepared in the form of acatalytic distillation structure: (b) concurrently in said distillationcolumn reactor (i) contacting said isobutylene with said first fixed bedmetathesis catalyst so as to react at least a portion of saidisobutylene to produce tetramethylethylene, ethylene, diisobutylene andheavier oligomers and create a reaction mixture containing unreactedisobutylene, ethylene, diisobutylene, heavier oligomers andtetramethylethylene product, and (ii) separating the ethylene andunreacted isobutylene from the tetramethylethylene, diisobutylene andheavier oligomers by fractional distillation; (c) removing the ethyleneand isobutylene from said distillation column reactor as a firstoverheads product; (d) removing the tetramethylethylene product,diisobutylene and heavier oligomers from said distillation columnreactor as a first bottoms; (e) separating said tetramethylethylene fromsaid diisobutylene and heavier oligomers by fractional distillationwherein said tetramethylethylene is removed as a second overheads andsaid diisobutylene and heavier oligomers are removed as a secondbottoms; (f) separating said diisobutylene from said heavier oligomersby fractional distillation; and (g) reacting at least a portion of saiddiisobutylene with at least a portion of the ethylene from saidseparator in a reactor containing a second fixed bed of metathesiscatalyst to produce neohexene and isobutylene.
 33. The process accordingto claim 32 wherein the isobutylene is separated from said neohexene byfractional distillation and the separated isobutylene is recycled tosaid distillation column reactor as feed.
 34. A process for theproduction of neohexene comprising the steps of: (a) feeding isobutyleneto a distillation column reactor containing a fixed bed of acidic cationresin catalyst prepared in the form of a catalytic distillationstructure: (b) concurrently in said distillation column reactor (i)contacting said isobutylene with said fixed bed catalyst so as to reactat least a portion of said isobutylene to produce diisobutylene andheavier oligomers and create a reaction mixture containing unreactedisobutylene, ethylene, diisobutylene, heavier oligomers and (ii)separating the ethylene and unreacted isobutylene from the diisobutyleneand heavier oligomers by fractional distillation; (c) removing theethylene and isobutylene from said distillation column reactor as afirst overheads product; (d) removing the diisobutylene and heavieroligomers from said distillation column reactor as a first bottoms; (e)separating said diisobutylene from said heavier oligomers by fractionaldistillation wherein said diisobutene is removed as a second overheadsand said heavier oligomers are removed as a second bottoms; (f) reactingat least a portion of said diisobutylene with at least a portion of theethylene from said separator in a reactor containing a fixed bed ofmetathesis catalyst to produce neohexene and isobutylene.